One participant, Kim Norris, said: ‘This is so much fun. It took me about a week to build up the courage to do this, and another week to talk my husband into it. But it was all worth it.’

The origins of the ritual are said to come from a bar room bet at the Mugs Away Saloon opposite the train track.

A punter apparently volunteered to buy a drink for anyone who would flash their bottom at a passing train.

The rest is history.

At one point the event attracted up to 10,000 people, but the Orange County Sheriff’s department has ‘cracked’ down on proceedings after some people over-zealously started having full sex by the tracks.

This year about 100 people took part with police officers patrolling to make sure there wasn’t any criminal naughtiness.